Physical vapor deposition (“PVD”) methodologies are used extensively for forming thin films of material over a variety of substrates. In one PVD process, known as sputtering, atoms are ejected from the surface of a sputtering target by bombardment with gas ions, such as plasma. Thus, the sputtering target is the source of material which is deposited onto a substrate.
A diagrammatic view of a portion of an exemplary sputtering assembly is shown in FIG. 1. A sputtering assembly 10 comprises a backing plate 12 having a sputtering target 14 bonded thereto. A semiconductor wafer 18 is positioned within the assembly and is spaced from a sputtering surface 16 of the sputtering target 14. In operation, particles or sputtered material 22 is displaced from the surface 16 of the sputtering target 14 and deposits on the surface of the semiconductor wafer 18 to form a coating (or thin film) 20 on the wafer. It is to be understood that the sputtering assembly 10 depicted in FIG. 1 is an example configuration since, for example, both the target 14 and the backing plate 12 can be any suitable size or shape. In some embodiments, the physical vapor deposition apparatus 10 may include the sputtering target 14 without the backing plate 12. This configuration is referred to as a monolithic configuration.
Various metals and alloys can be deposited using PVD technology, including for example Al, Ti, Cu, Ta, Ni, Mo, Au, Ag, Pt, and alloys of these elements. One such alloy is copper manganese (“CuMn”) which has been used in sputtering targets to form, for example, various metal interconnects used in the semiconductor industry. Current CuMn alloy sputtering targets contain less than 1 wt % Mn.
Additionally, advances in semiconductor wafer fabrication technology have led to a demand for larger sputtering target configurations, such as 300 mm and 450 mm sputtering targets (i.e. targets for use in 300 mm or 450 mm silicon wafer deposit processes). High sputtering power is also being used to improve throughput, film quality, and uniformity. However, high sputtering power may increase the risk for deflection and warping in conventional sputtering targets. Therefore, there is a desire in the semiconductor industry for a sputtering target with a higher strength to limit deflection.